* `salt.states.pip.installed()` now keeps a reference to the output of the `__salt__['pip.install']()` call. The reason for this is that we need to know and pass along any information about an eventual error when running that call. This is now done in addition to the old behaviour.
* Add some tests which triggered the issue.
* `salt.modules.file.contains()`, `salt.modules.file.contains_regex()`, `salt.modules.file.contains_glob()` and `salt.utils.find` now do the searching/matching against chunks of data; using defaults, 32KB chunks of data in files; instead of searching/matching line by line.
* Based on the above changes `salt.states.file.append()`, when checking if the text to append is already present, now uses `salt.modules.file.contains_regex()` in order to match spanning multiple lines ignoring the addition/deletion of white-space or new lines, except inside commas.
* The regex used on the above item is built at runtime using `salt.utils.build_whitepace_splited_regex()`, just feed the text to it and you'll get back the proper regex to the matching/searching on, for example `salt.modules.file.contains_regex()`.
* Added tests for all this code.
